1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element.
2. Related Art
A liquid ejecting head is used as a component of a liquid ejecting apparatus such as an ink jet printer. In an ink jet printer, a liquid ejecting head is configured to eject and fly droplets of ink such that the ink is made to adhere to media such as paper sheets. In this way, printing is performed with the ink jet printer.
In general, such a liquid ejecting head includes an actuator that applies pressure to liquid to thereby eject the liquid from nozzles of the liquid ejecting head. Such an actuator includes, for example, a piezoelectric element. For example, such a piezoelectric element in an actuator has a structure in which a piezoelectric layer composed of a piezoelectric material having an electromechanical transduction function such as a crystallized piezoelectric ceramic is sandwiched between two electrodes. Such a piezoelectric element is configured to deform under the application of a voltage by the two electrodes. Due to the deformation of the piezoelectric element, the actuator can be operated in, for example, a flexural vibration mode.
Piezoelectric materials used for such an application desirably have a good piezoelectricity such as electromechanical transduction efficiency. Accordingly, lead zirconate titanate (PZT) materials, which are excellent in terms of the piezoelectricity compared with other materials, have been studied and developed. However, while there has been an ever increasing demand for piezoelectric materials with enhanced piezoelectricity and there has also been a demand for piezoelectric materials having a lower environmental load in recent years, it is difficult to meet these demands with PZT materials. Thus, for example, perovskite-oxide piezoelectric materials, which have less lead content, have been developed.
The piezoelectricity of piezoelectric elements can be evaluated with the shape of a hysteresis loop obtained by subjecting the piezoelectric elements to a P-E measurement. Bismuth sodium titanate, which can be represented by, for example, (Bi0.5, Na0.5)TiO3 (hereafter, sometimes abbreviated as “BNT”), has been regarded as a promising piezoelectric material. However, although BNT in the form of a bulk exhibits a general hysteresis loop, in spite of the same BNT composition, BNT in the form of a thin film has a high leakage current and does not exhibit a good hysteresis loop (For example, refer to JP-A-2005-105295).